• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.160-163
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• 1995

본 硏究는 現在 일상적 있는 재생조골재를 죠오크러져(modified-jaw crusher)를 이 용하여 다시 1-3 파쇄를 행함으로써 재생골재의 품질이 어느정도 개량될 수 있는가를 실험 적으로 구명하여 재생골재의 실용화를 위한 하나의 방법을 제한하고자 하는 것이다. 실험결 과,재화파생 처리를 행하지 않은 경우의 재생근 골재의 흡수율은 5-7%정도이나 재파쇄를 함에 따라 흡수율은 현저하게 낮아져, 3차례의 재파쇄를 행한 경우 흡수율이 2% 이래로 나 타나 재생근골재의 품질을 학보하기 위하여는 재파쇄가 매우 유용한 방법임을 알 수 있었 다. 또한 흡수율의 본포도 처음에는 2개의 범주를 가지고 넓게 산포하게 되나 재파쇄가 진 행될수록 재생근골재중에 부착되어 있던 모르터분이 점차 떨어져 나감에 따라 품질의 산포 가 상당히 낮아지는 결과를 얻었다. 그러나 이와같은 재파쇄에는 많은 실용적 부담이 발생 하게 되므로 골재의 품질과 경제적효율을 고려하여 정적한 재파쇄회수가 결정되어야 할 것 으로 사료 된다.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.483-491
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• 2021

The purpose of this study is to analyze the economic effect of the use of recycled aggregate on the construction industry and the effect of increasing the value of the recycled aggregate production industry on the premise of supporting quality assurance technology to promote the high-quality use of recycled aggregate. Accordingly, the production cost of ready-mixed concrete that can be obtained through the use of high-quality recycled aggregate is analyzed according to the recycled aggregate application rate recommended in the recycled aggregate quality standard, The economic effect of general ready-mixed concrete and recycled aggregate-applied rea dy-mixed concrete industry wa s a na lyzed by identifying the domestic rea dy-mixed concrete industry sca le a nd the ra te of satisfaction of recycled aggregate volume, and a cost-benefit analysis method was used to examine the benefits of high-quality recycled aggregate production and sales. As a result, the production cost of ready-mixed concrete is reduced by 2.3~16.2% depending on the application rate, the economic effect of the use of recycled aggregate on the construction industry is about 106.8~142.6 billion KRW, and the effect of increasing the value of the recycled aggregate production industry generated about 1.22 times the benefit.

• 레미콘
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• s.85
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• pp.58-69
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• 2005

본자료는 건설교통부에서 마련한 순환골재 품질기준 중 콘크리트 분야만을 발췌하여 회원사 업무에 도움주고자 편집게재 합니다. -편집자주

• Journal of the Korea Institute of Building Construction
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• v.24 no.2
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• pp.239-248
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• 2024

The adjustment in guidelines for quality certification of recycled aggregate permitted the Quality Control Manager of a company specializing in recycled aggregate quality certification to concurrently assume the role of Environmental Management Manager. Analysis of the outcomes from the 2023 recycled aggregate quality certification follow-up management audit conducted by the certification agency revealed that in 95 out of 242 cases, constituting approximately 39% of the total cases, individuals held concurrent positions. Following the regulatory revision, there has been a notable proliferation of concurrent roles across various enterprises. Concerns arose regarding the potential neglect of quality control for certified recycled aggregates in comparison to scenarios where individuals are solely responsible for specific duties related to quality and environmental management. Audit results encompassing six aspects, including waste management, were evaluated on a scale of 6 points. A comparative analysis was conducted between the outcomes of 147 cases managed by dedicated personnel, as previously practiced, and 95 cases managed by individuals with concurrent roles. Although the average score of the latter group was marginally lower, no statistically significant disparity was observed between the two groups. Consequently, apprehensions regarding the oversight of quality control stemming from the allowance of concurrent roles appear unfounded. Within the context of recent regulatory revisions, permitting concurrent roles in managerial capacities is deemed an appropriate relaxation of regulations.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.485-488
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• 2008

Recycled fine aggregate has low quality because it contains large amount of old mortar. So, its usage is limited to a lower value-add, such as the roadbed material etc. Also, alkaline water occurred from treatment process of the waste concrete is becoming the cause of environmental problem. Accordingly, this study is to develop on the high quality recycled fine aggregate produced by low speed wet abraser using sulphuric. We investigated the properties of compressive strength of the mortar which was manufactured using recycled fine aggregate containing calcined gypsum produced by earlier mentioned process. Test results indicate that mortar using recycled fine aggregate containing calcined gypsum has lowest compressive strength. It seems that low compressive strength is closely associated with the expansion of the specimen by excessive formation of ettringite.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.2
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• pp.125-135
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• 2016

The objective of this paper is to provide integrated Korea industrial standards(KS) for concrete aggregates, which has been separately provided with ten kinds of KS, in order to improve the way of quality management of concrete aggregate and to prevent distribution of unsuitable aggregates. For the sequences of the paper, typical foreign standards related to concrete aggregates including ASTM for US, EN for EU, JIS for Japan are reviewed and compared to provide necessities and feasibilities of the paper. Based on the analysis above results, existing KS for concrete aggregates, which have been separately provided with ten kinds being lack of correlation between each KS is integrated to KS F 2526 "Aggregates for concrete" in this paper. By doing this, in terms of terminology, the expression of the aggregate, which has been currently classified into specified terminologies of aggregates depending on sources, manufacturing methods of each aggregates, is able to be integrated to single expression of the aggregate for concrete. It is believed that integrated KS presented herein provides more desirable way in terms of its better accessibility, easier revision and closer connection between each aggregate kinds.

• Journal of the Korea Institute of Building Construction
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• v.15 no.6
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• pp.561-567
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• 2015

The research, in order to enhance the quality of recycled aggregate, was carried out the quality characteristics test of the recycled aggregates by applying the four kinds of surface treatment using a colloidal suspension of approximately 5nm~60nm particle size with the alkalinity of pH 10.2. The quality tests of recycled aggregate have been processed by specific gravity, water absorption, porosity, surface properties, and the compression and tensile tests. The colloidal suspension was coated effectively the surface of the old cement mortars of recycled aggregate with a constant thickness by colloidal suspension is being applied to the recycled aggregate surface under constant pressure of 100kpa and then it was dried in at $60^{\circ}C$. The surface treatment method by the Method C out of 4 kinds of surface treatment improved effectively the quality of the recycled aggregates, whereby it obtained the best compressive strength and tensile strength of the recycled aggregate concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.481-484
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• 2008

Recently, the recycling and reusing of construction and demolition waste concrete is urgently required because waste concrete is greatly increased according to the rapid increasing of urban redevelopment project, but the problem solution for demand and supply unbalance of fine aggregate is urgently required because of the restriction of collecting sea fine aggregate. So the utilization of high quality recycled fine aggregate using construction and demolition waste concrete as new fine aggregate for construction industry is urgently. Accordingly, In this study, As recycled fine aggregate manufacturing technology with exceeding in economical efficiency, reduction efficiency of environmental load and quality improvement effect of recycled fine aggregate, it is to develop dry manufacturing system composed specific gravity separator of high-speed rotation impact type and centrifugal Force Powder Collector, etc. And it is to examine mechanism of recycled sand dry manufacturing system.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.4
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• pp.341-348
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• 2019

In this study, we analyzed the problems of existing construction waste shredding technology to diagnose the problems of low quality recycled aggregates and to develop a new mortar peeling technique to produce high-quality recycled coarse aggregate for concrete. The purpose of this study is to verify the effectiveness of mortar peeling technique by doing simulation prior to on-site application and to check the quality properties of recycled coarse aggregate produced by applying a mortar peeling technique. We manufactured and installed High speed Rotating Grinder on-site and analyzed the correlation between mortar adhesion amount, dry density and water absorption rate of recycled coarse aggregate.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.2
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• pp.97-102
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• 2011

Amount of disposed construction materials like waste concrete is growing fast and use of the recycled aggregate for concrete has been seriously considered. But the use of the recycled aggregate is very limited because recycled aggregate has very low quality. Therefore, quality of recycled aggregate is very important in the manufacturing of recycled aggregate concrete. We have studied a series of research according to chemical processes and investigate the alkaline elimination effect of recycled aggregate and quality variation of recycled aggregate by sodium carbonate. Thereafter we have evaluated quality of recycled fine aggregate and experimented quality of this aggregate. As a results, we find that it is easy to eliminate the calcium hydroxide in recycled aggregate by sodium carbonate and the quality of recycled aggregate increase by elimination of alkaline.